Basically, pressure on Port2 cannot be higher than pressure on Port1 (P1 should be always greater or equal P2), in the case of the MPL115A2, since it’s an absolute pressure sensor, Port2 it’s sealed at a specific pressure, but, you don’t need to worry about it on the sealed bag vacuum package sent with the MPL115A2 devices, since in this package pressure on Port1 should not be lower than pressure on Port2.

In fact, if you are still worried about the possible negative pressure on the package that could be affecting the pressure sensor (which is not being damaged), then I would recommend you to remove them from the vacuum package, the MPL115A have a MSL level of 1 and an FLOOR life defined as UNLIMITED, so there is no risk on moisture issue.